const { series, parallel } = require("gulp")
const task1 = done => {
  setTimeout(() => {
    console.log("task1 is working");
    done();
  }, 1000);
}
const task2 = done => {
  setTimeout(() => {
    console.log("task2 is working");
    done();
  }, 1000);
}
const task3 = done => {
  setTimeout(() => {
    console.log("task3 is working");
    done();
  }, 1000);
}

// 串行
exports.foo = series(task1, task2, task3)

// 并行
exports.bar = parallel(task1, task2, task3)